You did not 'fall in love' with her. You became infatuated and obsessed. With a woman you were/are not in a relationship with.
"... for so-called 'professional' reasons (complicated) she doesn't want to see me."
That's called 'letting them down gently'. 'Being polite'. Maybe being a little afraid of the guy radiating stalker vibes (the "so-called" definitely gives me those vibes) who doesn't want to take NO for an answer.
Truth is, you're not asking her to 'consider a friendship'. You're insisting on a relationship (that you know she doesn't want) which you will CALL friendship, but you will always be pushing for more. 'Guarding' her from starting an actual relationship with another man. Cockblocking. Guess what? She doesn't owe you any form of relationship whatsoever. Not romantic, not friendship, not even acquaintanceship. Nowt.
You started another thread today, which I encountered before this one.
https://www.mumsnet.com/talk/relationships/4668338-would-you-keep-an-expensive-beautiful-necklace-from-a-guy
You asked in your OP of that thread:
"Would you keep an expensive beautiful necklace from a guy that a few days later you told you never wanted to see again and not to contact you any more - although he'd never done anything to hurt you and had only been nice and gentle? Clearly it meant a lot to him and he wouldn't have given it to you in the first place if he wasn't crazy about you."
and in response to another poster:
"the gift represented the way I felt about her - no other context. And when she accepted it she initially told me 'it was too much' but also declared "I will wear it". It was bleeding obvious how I must have felt. I have no hard feelings about it and I want her to keep it but I'm trying to understand the psychology behind its acceptance and use."
You never made clear on that thread what is clear on this thread - that you are not in a relationship with her. The answers you received would have been very different had you included that detail. I know my answer would have been very different.
When she said 'I will wear it' - that's what you respond when you've got creepy stalker guy in front of you and you're afraid of what he'll do if you don't respond like that. So, the "psychology behind its acceptance" is - fear. Fear of the person who is not behaving in a normal rational way. Fear.
Leave her alone.